Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF JOINING PIPE SEGMENTS USING AN ADHESIVE
COMPOSITION
PRIORITY CLAIM
[0001] This application claims priority under 35 U.S.C. 119(e) to U.S.
Provisional Application Serial No. 61/234,586, filed August 17, 2009, which is
expressly incorporated by reference herein.
BACKGROUND
[0002] The present disclosure relates to a composition for joining and sealing
two structures, such as two sections of pipe. More particularly, the present
disclosure
relates to a composition forming a corrosion-resistant protective coating to
cover a
pipe joint and to a method of forming a pipe joint using a shrink sleeve.
SUMMARY
[0003] The present disclosure includes a composition joining two sections of
pipe. In illustrative embodiments, the present disclosure provides, in one
exemplary
embodiment, a method of forming a corrosion-resistant protective coating on a
pipe or
joint, comprising: (a) providing a section of pipe containing at least one
joint; (b)
providing a sheet of an adhesive composition comprising an acrylic-based
adhesive
and an initiator; (c) applying the adhesive composition to the pipe section;
and, (d)
exposing the adhesive composition to UV light for a sufficient period of time
so as to
cure the adhesive composition and form a permanent coating on the pipe
section.
[0004] Another aspect of the present disclosure provides a method of forming
a corrosion-resistant protective coating on a pipe or conduit joint,
comprising: (a)
providing a section of pipe containing at least one joint and a line coating
area; (b)
providing a sheet of an adhesive composition comprising a 2-ethyl-hexyl
acrylate and
an initiator; (c) wrapping the adhesive composition onto the pipe section so
as to
overlap the line coating area edges; and, (d) exposing the adhesive
composition to UV
light for between about 1 and about 6 minutes so as to cure the adhesive
composition
and form a permanent coating on the pipe section.
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DETAILED DESCRIPTION
[00051 In one exemplary embodiment the present disclosure provides a
composition comprising a LTV curable monolayer adhesive. The material may be
an
acrylic-based adhesive composition. It is preferable that the adhesive
composition be
either transparent or translucent. The adhesive composition may be an epoxy-
type
adhesive, but, it is preferable that the composition not be brittle. It is
preferable that
the adhesive composition possess a certain amount of tackiness, for example,
by
incorporating a tackifier material, such as in the film. Alternatively, the
composition
may possess pressure sensitive properties. The composition preferably can
adhere to
steel and to polypropylene line coating to create a permanent or a strong
bond, and
provide the joint area protection from corrosion and resistance to exposure to
chemicals, vapor, and the external environment.
[00061 A number of acrylic-based adhesives can be used. Examples include,
but are not limited to, one or more 2-ethyl-hexyl acrylates ("2EHA"),
optionally
including other initiators. For bonding to polypropylene, an adhesive
composition
formulated for polypropylene is preferred.
[0007] Pressure sensitive adhesives which may be usable with the
composition and method of the present disclosure are described in
International
Publication No. WO 2008/116033 A2 (International Application No.
PCT/US2008/057574) entitled "Pressure Sensitive Adhesives and in International
Publication No. WO 2009/117654 Al (International Application No.
PCT/US2009/037800) entitled "Acrylic Polymers Having Controlled Placement of
Functional Groups" (the disclosures of both documents being incorporated by
reference in their entirety herein).
[00081 Upon exposure to UV light the adhesive composition will crosslink
and harden, while adhering to the substrates in which it is in contact to form
a
structural bond.
[00091 One exemplary method of forming a seal comprises a first step of
providing two sections of pipe in an abutting relationship. A second step is
to apply
the adhesive composition to the pipe joint area overlapping the edges of the
line
coating. The protecting coating can be applied to the joint area by any of a
number of
techniques known to those skilled in the art, such as, but not limited to,
spraying,
troweling, painting, squeegeeing, pumping via a conduit from a reservoir, hand-
applying, using a glue gun or other pressurized liquid dispenser, dispensing
from a
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tube, or the like. A third step is to expose the wrapped adhesive composition
to UV
light for several minutes to initiate the reaction and complete the curing of
the
composition. The time of exposure to UV light may vary depending on the
composition, the thickness of the adhesive layer, the transparency of the
composition,
the energy level emitted by the UV source, further initiator content, and
other
parameters. In general, one exemplary range of curing time may be in the range
of
about 1-6 minutes. Preferably, the curing time may be in the range of about 2-
5
minutes. More preferably, the curing time may be in the range of about 2-3
minutes.
Shorter (or possibly longer) cure times may be used depending on various
factors,
including those described hereinabove. It is preferable for the applied
coating to be
exposed to UV light generally uniformly around the circumference of the
exposed
surface. This may be accomplished by using several UV light sources, a single
UV
light source plus mirrors (or other reflective or directing or focusing means)
positioned at various angles around the pipe joint area, curved UV light
sources, or
other suitable configurations. The UV light can penetrate substantially the
entire film
layer because the film is either transparent or translucent; thus, curing of
all or
substantially all of the film will occur.
[00101 In another exemplary embodiment, the adhesive composition as
disclosed above can be applied to the joint area and then a layer of
transparent film,
such as, but not limited to, a film, tape, shrink sleeve or the like,
comprising, for
example, a polyolefin-based material, can then be wrapped around the area in
which
the adhesive composition is applied. The wrapped film may be maintained in
place by
any of several mechanisms known to those skilled in the art. Then both the
adhesive
composition and the transparent film can be cured at the same time as
described
hereinabove. The film layer can function as a protective layer to provide
mechanical
protection and prevent damage to the joint coating during handling. For the
purposes
of the present disclosure, the term film is intended to mean a generally flat
sheet of
material which is preferably solid (to provide a relatively impermeable
barrier when
applied and cured). The film may optionally incorporate at least one
reinforcing
material, such as, but not limited to, fibers, threads, filaments, granules,
powder, a
mesh, a grid, combinations thereof, and the like. The reinforcing material may
be
Fiberglas or other material. The film may be formed as a sheet, roll, tape,
patch, or
other shape or configuration.
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[0011] The compositions and methods disclosed herein are well-adapted for
use in joining pipe units to form a continuous elongated pipe to be deposited
onshore
or offshore along a sea bed by a lay barge. By using a UV-curable adhesive
film as
described in the present disclosure, the process is simplified and the time to
install the
adhesive is reduced compared to heat-activated shrink sleeves, which is
essential to
field applications, especially offshore jointing activities, which are
normally time
sensitive. The presently disclosed method reduces installation time, in part,
because of
the elimination of the pre-heating time of the steel surface (for steel pipe
jointing) and
elimination of the cooling time associated with heat-activated shrink sleeve
installation. Greater control over application accuracy is also provided,
which ensures
a void-free sealed surface. The simplified procedure reduces the chance of
operator
application error. Furthermore, the present disclosure eliminates the use of
open
flames (e.g., gas torch) to shrink a sleeve. The method as described herein
also
maintains its efficiency in cold temperature, windy, or wet environments.
[0012] The compositions and methods disclosed herein can be used in a
variety of applications where heat-activated shrink sleeve methods or other
heat or
irradiation curing methods may be currently used. The present disclosure is
well-
adapted for use where the pipe or conduit material to be joined is heat
sensitive (for
example, PVC, Plexiglas, glass, ceramic, wood, or the like) or where heat or
an open
flame is not advisable or dangerous (such as were volatile vapors are
present).
Furthermore, the present disclosure is not limited to joining pipes; it can be
used to
apply an adhesive to any type of substrate or substrates, be it flat or
irregular shaped
surfaces or joining different types of materials (for example, joining PVC to
steel or
joining PVC to Plexiglas).
[0013] Unless otherwise expressly stated, it is in no way intended that any
method set forth herein be construed as requiring that its steps be performed
in a
specific order. Accordingly, where a method claim does not actually recite an
order to
be followed by its steps or it is not otherwise specifically stated in the
claims or
descriptions that the steps are to be limited to a specific order, it is no
way intended
that an order be inferred, in any respect.
[0014] The disclosure will be further described in connection with the
following examples, which are set forth for purposes of illustration only.
Parts and
percentages appearing in such examples are by weight unless otherwise
stipulated.
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EXAMPLES
[0015] Example 1
[0016] Preparation of Random Acrylic Polymer Containing Methacrylic Acid.
(Low Molecular Weight Version)
[0017] An acrylic copolymer with methacrylic acid distributed randomly
throughout the polymer backbone was prepared as follows. Into a 1,500ml
reactor
equipped with a heating jacket, agitator, reflux condenser, feed tanks and
nitrogen gas
inlet there was charged 54.8g of ethyl acetate, 8.87g isopropanol and 25.06g
acetone.
Monomers were added in the following amounts:
[0018] 74.3g butyl acrylate
[0019] 20.37g tert-butyl acrylate
[0020] The reactor charge was heated to reflux conditions (reactor jacket
85 C) with a constant nitrogen purge. Once solvent reflux was attained, an
initiator
solution of 0.19g benzoyl peroxide (LuperoxTM A) and 4.24g ethyl acetate was
added
to the reactor. After a peak temperature of 76-78 C was attained, a reagent
feed
mixture with an active nitrogen purge of 286.3g ethyl acetate, 31.8g
isopropanol,
364.9g butyl acrylate, 100.Og tert-butyl acrylate, 2.96g methacrylic acid and
1.04g
LuperoxTM A was added over a period of three hours to the reactor. Over the
three
hour reagent feed the temperature of the reaction was held under reflux
conditions at
75-79 C. The reaction conditions were maintained for 30 minutes after
completion of
the reagent feed. A mixture of 1.54g t-amylperoxy pivalate (LuperoxTM 554) and
37.15g of ethyl acetate was added to the reactor over a period of 30 minutes.
The
reaction was held at reflux conditions for an additional hour at which point
it was
diluted with 120g of ethyl acetate. The resulting solution polymer was then
cooled to
ambient temperature and discharged from the reactor.
[0021] The resulting acrylic polymer contained 77.93% butyl acrylate,
21.36% tert-butyl acrylate, and 0.526% methacrylic acid based on 100% by
weight of
the acrylic polymer. The molecular weight of the acrylic polymer was
30,800g/mole
(determined by gel permeation chromatography relative to polystyrene
standards) and
the polydispersity was 3.1. Then, 210g of 100% solids polymer was dissolved in
90g
of ethyl acetate to yield a solution acrylic.
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[0022] Physical Testing:
Solids 52.8 Tsc% 40 min. in 120 C oven
Viscosity 590 cps Brookfield RV Viscometer, spindle
#5 @ 100 rpm, 73.6% torque
% Conversion 98.0% gas chromatography
[0023] Aluminum acetoacetonate in an amount of 1.0% based on solids and
20% based on solids terpene phenolic resin was added to the acrylic polymer.
The
adhesive composition was dried at 90 C for 20 minutes to ensure complete cross-
linking of the acrylic polymer.
[0024] Example 2
[0025] The material of Example 1 was diluted to 30,000 CPS (Brookfield
viscometer, spindle #5, 10 rpm) with ultraviolet and thermally curable
diluents. The
adhesive composition was coated onto a metal (steel) substrate and a polyester
release
film was applied to level the adhesive to 30 to 40 mil thickness. The film was
exposed
to 950 milli-Joules/cm2 of radiation from a 600 watt metal halide bulb for
about 60
seconds and then post-cured at 130 C until a cured film resulted.
[0026] Example 3
[0027] The film of Example 2 had the following properties:
Thickness 75 mils
Pull-off adhesive strength (using ASTM standard 1st sample: 2850 psi
D4541) 2nd sample: 1301 psi (glue failure)
Impact strength (using ASTM standard G14) >120 in. lb at room temp. (23 C);
99 in. lb at -5 C
